- Spontaneous conversion of prenyl halides to acids: application in metal-free preparation of deuterated compounds under mild conditions
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Here we reveal a simple generation of deuterium halide (DX) from common and inexpensive reagents readily available in a synthetic chemistry laboratory,i.e. prenyl-, allyl-, and propargyl halides, under mild conditions. We envisaged thatin situgeneration of an acid, deuterium halide, would be useful for acid-catalyzed reactions and could be employed for organocatalytic deuteration. The present work reports a metal-free method for deuterium labeling covering a broad range of substrate including phenolic compounds (i.e. flavonoids and stilbenes), indoles, pyrroles, carbonyl compounds, and steroids. This method was also applied for commonly used drugs such as loxoprofen, haloperidol, stanolone, progesterone, androstenedione, donepezil, ketorolac, adrenosterone, cortisone, pregnenolone, and dexamethasone. A gram-scale chromatography-free synthesis of some deuterated compounds is demonstrated in this work. This work provides a simple, clean and by-product-free, site-selective deuteration, and the deuterated products are obtained without chromatographic separation. When applying these initiators for other acid-catalyzed reactions, the deuterium isotope effects of DX may provide products which are different from those obtained from reactions using common acids. Although the mechanism of the spontaneous transformation of prenyl halides to acid is unclear, this overlooked chemistry may be useful for many reactions.
- Darshana, Dhanushka,Sureram, Sanya,Mahidol, Chulabhorn,Ruchirawat, Somsak,Kittakoop, Prasat
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supporting information
p. 7390 - 7402
(2021/09/07)
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- ACTIVATION OF WATER MOLECULES - 2. GENERATION OF STRONG HYDROXO BASES BY THE REACTION OF WATER WITH PLATINUM (0) PHOSPHINE COMPLEXES AND THE APPLICATIONS AS CATALYSTS FOR H-D EXCHANGE AND HYDRATION REACTIONS.
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The dissociation of Pt(PEt//3)//4 in organic solvents (THF, n-heptane) occurs to give Pt(PEt//3)//3 L equals 0. 5 M in THF at 20 degree C), no further dissociation being detected, while Pt left bracket P(i-Pr)//3 right bracket //3, upon dissolution in the above solvents, exists mainly as Pt left bracket P(i-Pr)//3 right bracket //2 (K//L equals 0. 14 M in THF at 20 degree chemical Addition of water to PtL//(L equals PEt//3//, P(i-Pr)//3) generates strong hydroxy bases, left bracket PtHL//3 right bracket OH (L equals PEt//3) or trans- left bracket PtH(S)L//2 right bracket OH (L equals P(i-Pr)//3//, S equals solvent), while the addition to Pt left bracket P(i-Pr)//3 right bracket //2 gives a sigma -hydrido hydroxo compound, trans-PtH(OH) left bracket P(i-Pr)//3 right bracket //2. Quantitative study on the reversible water addition to PtL//3 in organic solvents was carried out by pH and conductance measurements. The conductometric behaviors of the system PtL//3(L equals PEt//3)/H//2O in pyridine and THF are described in terms of two equilibria. The mechanism was studied for H-D exchange of C//6H//5COCH//3 to show that the reaction follows a rate equation, R equals k left bracket Pt right bracket left bracket C//6H//5COCH//3 right bracket , and involves a reversible condensation, M** plus OD** minus plus C//6H//5COCH//3 reversible reaction MCH// 2COC//6H//5 plus DHO, as the rate-determining step. Unlike the alkaline base-catalyzed reaction, alpha -olefinic, allylic, and aldehydic hydrogen atoms of alpha , beta -unsaturated carbonyl compounds were exchanged. The hydration of the nitrile and double bonds of RCH equals CHCN catalyzed by left bracket PtHL//3 right bracket OH or left bracket PtH(S)L//2 right bracket OH and trans-Pt(OH)(R)(PPh//3)//2 occurs with excellent chemical yields.
- Yoshida,Matsuda,Okano,Kitani,Otsuka
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p. 2027 - 2038
(2007/10/05)
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